Fibre isn't just roughage.

Mechanisms of Fibre

• Mechanism 1: Viscosity (The Regulator): Soluble fibres absorb water to form a gel-like matrix. This physically slows gastric emptying, which blunts dangerous blood sugar spikes and traps cholesterol before it enters the bloodstream.
  Source: Viscous Dietary Fiber and Metabolic Profile (The American Journal of Clinical Nutrition)

• Mechanism 2: Bulking (The Sweeper): Insoluble fibres remain intact as they pass through the digestive tract. They mechanically stimulate the gut wall, accelerating "transit time"—reducing the amount of time carcinogens and toxins sit in contact with your colon cells.
  Source: Dietary Fiber and Transit Time: A Meta-Analysis (World Journal of Gastroenterology)

• Mechanism 3: Fermentation (The Fuel): Perhaps the most critical modern discovery. Resistant Starches bypass digestion entirely to reach the colon. There, they ferment to produce Short-Chain Fatty Acids (like Butyrate), which serve as the primary energy source for repairing colon cells.
  Source: Resistant Starch: Health Benefits and Mechanisms (Advances in Nutrition)

The Modern Diet and its Consequences

• The 95% Failure Rate: Current epidemiological data reveals that less than 5% of the adult population meets the adequate intake for dietary fibre. The remaining 95% are chronically deficient, starving the gut microbiome of its primary fuel source.
  Source: Closing America’s Fiber Intake Gap (Quagliani & Felt-Houlihan, 2016)
  

• The Satiety Deficit: Modern food processing systematically strips away the fibrous matrix of plants. Without this essential bulk, the body’s natural "fullness" signals are bypassed. This caloric density without volume leads to a cycle of rapid consumption and constant hunger, despite adequate energy intake.
  Source: The Impact of Dietary Fibre on Satiety (Slavin & Green, 2007)